Aspects of diffractive physics: Introduction of non-perturbative effects

English

Dechambre, Alice[Université de Liège - ULg > Département d'astrophys., géophysique et océanographie (AGO) > Interactions fondamentales en physique et astrophysique >]

20-Jun-2007

Université de Liège, Liège, Belgique

Diplome d’Etude Approfondies en Sciences

73

Cudell, Jean-René

Dauby, Pierre

Cugnon, Joseph

Lech, Szymanowski

[en] Non-perturbative physique ; Diffraction

[en] We think of this work as a basis, a kind of manual or short report on topics, tools and methods for diffractive high-energy calculations and as an example of what is possible to do, but also as a bridge to new approaches to the introduction of non-perturbative effects and to more complex calculation.
We introduce the necessary ingredient to understand diffractive production. The first chapter is an introduction to cutting rules, Feynman diagrams and we shall see that the main part of the cross-section information is given by the imaginary part of these diagrams. After the introduction of our technique of calculation we come to the pomeron physics and introduce the approach of our futur calculation. The last subsection is devoted to the first step in the direction of the Higgs diffractive production, a two-loop diagram as a basis of our future works. The last chapter will contain an original result. We know that QCD has some problems especially with non-perturbative phenomena i.e. long-distance events. A long-time ago, Gribov introduced the idea of a modified gluon propagator that includes non-perturbative effects in the usual calculation of the amplitude. Then, we shall take this Gribov propagator and perform the calculation of the two-gluon exchange with it. We conclude by a review of the improvement needed in the calculation and the new aspects of the amplitude.